When a mass evacuation of Houston occurred due to Hurricane Rita, 107 people died from the conditions caused by the mass evacuation. The conditions on the roads were very very poor for those following your suggested advice of "heeding the warnings". The storm in the end was not as big of an event as it was made out to be.

It's not as simple a decision as you're making it out to be.

https://en.wikipedia.org/wiki/Hurricane_Rita#Evacuation_deat...